9Xtreme Upgrade Board for 9x Radios

Post by **s_mack** » Sun Sep 27, 2015 12:33 am

I started to wonder if we couldn't take the 6-wire almost out of the equation entirely and just use it as an indicator if the switch is up/down but don't actually put power through it (ie as a signal only). That way that voltage regulator wouldn't have any current going through it, we rid ourselves of that convoluted mess, and we can then fully control a single-point pathway of the battery input. Meh... rev 1.2

Post by **jhsa** » Sun Sep 27, 2015 3:08 am

Steven, what do you mean? Without the 6 pin connector the 9x would be powered by its own regulator instead of receiving the 5V from the 9xtreme?

João

Post by **s_mack** » Sun Sep 27, 2015 3:22 am

No. As it is, the power goes from the battery (connected to the back plane), through the 12-wire cable into the 12-pin header of the 9X board then, for some weird reason, along the 9X board to the 6-pin header, up through the 6 wire cable where it gets to the switch. Then, from the switch, it travels back down the 6 wire cable (a different wire depending if the switch is ON or OFF) where it is then taken to the voltage regulator AND back over the 12-wire and up a different wire, again depending on the switch's state, back to the back plane.

The reason they did it this way was, I think, because there are different requirements depending on if the switch is ON or OFF and also if the trainer port is being used or not. As I said before, it is convoluted. Or genius. I'm not really sure which.

With the 9Xtreme, we hijack both the 12 and 6 pin cables. With the current design, we only truly hijack the lines we felt we needed, passing the others on as they were. What I'm suggesting is that we render the switch nothing more than... well... a switch. Right now it is a little more than that. OK, it is still just a switch, but it does more than ON/OFF. It dis/allows certain functions depending on that state. Such as charging vs. trainer, etc. I'm saying maybe we handle that circuitry as well and just use the switch as an on/off.

The difficulty is going to be how to deal with the trainer, simulator and charge logic. I personally have never used any of those functions, so I'm sure I'm not the most qualified to be pondering this

Left to my own devices, it is quite possible I'd end up wrecking how some people use the thing.

But I'm looking at the circuitry now and I think the reason we've gotten into trouble here is we have no control over what happens AT the switch once we flow power through it.

Anyway, I'm filing this away for now. It is far too premature to even be considering a 2nd batch. I don't know if there's even enough people to buy the 1st! I hope so, but I can't presume.

I'll reiterate that this really shouldn't be of any concern to anyone ever reading this... because you all are fully versed on plugging in your battery correctly. The people that need this (unfortunately absent) feature are the ones who aren't reading here, aren't really familiar with electronics. The type that see that a 2S balance plug looks invitingly similar to the stock 9X battery connector and don't think twice about it. I would LOVE to give them the protection they need (and we tried), but I'll have to settle for providing good tips and warnings in the installation instructions.

Post by **jhsa** » Sun Sep 27, 2015 3:49 am

The radio also reads the switch position to decide whether to set the trainer as input or as output as far as I know. If you connect a trainer cable it will power up and start sending PPM out. But if you turn the power switch ON it will immediately set the trainer as input and will expect a valid signal on the trainer port. But yeah, as you say it might be too early to even think about it

I'm looking forward to have mine and start messing with it. First job, fixing the reverse battery protection before I have a senior moment. It can happen to everyone, specially if you're not good at multitasking

João

Post by **MikeB** » Sun Sep 27, 2015 11:41 am

This is the mod I've done to the 9Xtreme (prototype) board to fix the reverse polarity problem:

: PowerMod.png (2.15 KiB) Viewed 9744 times

The track cut needs to be right on the edge of the pad of the pin, as you are only disconnecting the pin, leaving all track still connected together. The diode is added between the connector pin and the track indicated.

This diode then block reverse current through the switch. While there is voltage drop across the diode in normal operation, this doesn't matter as the soft power switch shorts it out so the diode is not then conducting.

For information, when you connect a trainer cable, this actually just turns the soft power switch on. There is also a separate circuit that tells the processor whether the power switch is on. So, if the processor is running, and the power switch is off, the processor knows it is in trainer mode.

Mike.

Post by **jhsa** » Sun Sep 27, 2015 11:57 am

Mike, is a schottky diode a good idea? I think they have more reverse current leakage than the other general use diodes.. Also what are the minimum specs for the diode?

What about something like on the picture? maybe without the Zener diode and resistor if the VGS voltage the FET can handle is higher than the radio supply.

Even if it is not a solution for this problem, it could be a solution for the normal 9x radio

Very easy to implement I would say..

João

Post by **MikeB** » Sun Sep 27, 2015 12:25 pm

I used a SS34, taken from an old pre-prototype board. This is rated at 40V reverse blocking voltage, average forward current of 3.0A.

A small current flowing when there is a reverse voltage is not a problem. In my testing I had up to 60mA flowing, when there was no protection, and nothing was damaged.

With the diode, I tested a reverse voltage of 12V, and all is OK.

We have a similar crcuit to the one you posted protecting the soft power switch circuit.

Mike.

Post by **jhsa** » Sun Sep 27, 2015 1:02 pm

Thanks Mike, I think I have some 3A schottky here as well from one of my unfinished projects

Will see which one and check the datasheet..

João

vahegan · Post by **vahegan** » Sun Sep 27, 2015 1:46 pm

I think it'll be easier to solder the Schottki between the connector solder point and the pin of the small FET or whatever it is in this position, rather than scrubbing the green stuff and soldering to the trace

KAL · Post by **KAL** » Sun Sep 27, 2015 1:59 pm

Hi folks,

here is my solution to "protect" the 78L05 on the switchboard:
(please don't take it too serious ...)

s.th that isn't there can't go faulty

Klaus

Post by **MikeB** » Sun Sep 27, 2015 2:03 pm

That will probably depend on the size of the diode as to whether it will fit or not. Either position for the diode will do.

I just removed the 78L05 from the switch board as well!

Mike.

bob195558 · Post by **bob195558** » Mon Sep 28, 2015 1:03 pm

For the Reverse Current Protection Mod is this SS34 Vishay DIODE SCHOTTKY 40V 3A SMC
(http://www.ebay.com/itm/20PCS-SS34-Vish ... 2a5236986c)
what should/could be used ?

Bob B.

Post by **MikeB** » Mon Sep 28, 2015 1:09 pm

That looks to be the same diode as I used.

Mike.

bob195558 · Post by **bob195558** » Mon Sep 28, 2015 4:35 pm

Thank You Mike!
If I recall correctly last year I had an incident which one early, before fully morning light and still quite sleepily
and without my needed glasses, proceeded to connect my fully recharged 3S Lipo battery to my 9x radio.
With my morning, fuzzy full confidence, in that I was able to perform this procedure without any trouble what so ever.

A Flash of Fire and Smoke

with my suddenness of adrenaline pumping through my body, which in short order cause me to be fully awake with thoughts of

I just smoked the power circuit in my 9x radio !

Investigating the power connecting plugs the 9x radio right ground pin was vaporized
and the 3S Lipo center + pin needed some cleaning up or I may have even replace it.
It looks like I had the plugs misaligned and pressed hard enough to just make contact between the wrong pins.
When properly connecting the two plugs together this 9x radio powered up with no problems.

To the Why and How the power circuit survived this Reverse Polarity current connection I do not know,
but I feel lucky it only damage the pins that just made contact with each other.
So for me, I want to do the 9xtreme Reverse Current Protection Mod
as its a good time to do it before installing the 9xtreme board.

Bob B.

Post by **s_mack** » Mon Sep 28, 2015 4:55 pm

That sounds like a short circuit, rather than reverse current. You basically turned your battery into an arc welder. I'm not really sure how you did that. What connector is on your battery?

bob195558 · Post by **bob195558** » Mon Sep 28, 2015 5:23 pm

Hi Steven,
Here is a picture of what I use with my 9x radios.

I change the 3S Lipo 11.1V battery, two pin plug to a 3 pin plug
and so was hoping to never have a problem with Reverse Polarity.
But I found it was not a guarantee and that it could happen.

Bob B.

Post by **s_mack** » Mon Sep 28, 2015 5:44 pm

with that setup, it should not be possible. That is a correctly wired, keyed plug. It should not be possible to plug it in wrong. Even if you managed to bend the the 9x pins so that they touched pos to neg... those arent charged at that point, so still nothing should happen.

Strange

Post by **Kilrah** » Mon Sep 28, 2015 7:03 pm

Either he connected the wrong plug (the other one fits but would obviously short the battery), or like some he removed the plastic shroud on the 9x pins allowing to connect the plug shifted.

Post by **s_mack** » Mon Sep 28, 2015 8:13 pm

The other one shouldn't fit... this is a 3S battery, meaning that balance plug is a 4 pin and physically would not fit. That's what I thought at first was that he plugged in a 2S's 3-pin balance and created a short.

If the ground pin "vaporized" then it was not a reverse polarity event, it was a short. I just can't see how a short would be possible with the battery pictured. Perhaps some metal debris? If the metal pins had something on them in the 9X somehow, then as the battery makes contact, that bridge would short the battery. That's about the only scenario I can envision, but man that would be unlikely.

Post by **s_mack** » Mon Sep 28, 2015 8:16 pm

Now that I look a little more carefully... are those wires exposed???? Or is that some grey paint or a scuff or something?

Post by **s_mack** » Mon Sep 28, 2015 8:40 pm

I think I might have a reasonable, low-tech, solution for the battery issue.

The main problem seems to be the varying connectors people might use. The worst culprits seems to be the use of non-polarized 2-pin wires connectors like the red one I've attached. The issue is that it can be inserted in 4 possible ways, 2 of which are OK and 2 create smoke (reverse polarity). That connector can plague any battery chemistry or cell count. The next issue is the inadvertent (or ignorant) use of a 2-cell LiPO's balance plug. This is inviting to the uninitiated because it looks (and is) identical to the stock 8xAA battery pack that comes with the 9X. It fits, so people put it in... and more smoke (battery short). Of course, that's only going to be a problem with 2S batteries so it probably is a more rare occurance since a stock 9X isn't that great on a 2S (the 9Xtreme is much better in that regard)

So the suggestion has always been to replace your battery's discharge plug with the one that came with the 8xAA holder, or to use a battery that comes with a 3-position servo-style plug (like the black one that comes with this highly recommended LiFE battery). The problem with the first recommendation is it requires soldering a battery, which not everyone is comfortable with. HobbyKing understands this, which is why they've tried to universalize their battery connections (to a degree). The problem with the 2nd recommendation, is not everyone is comfortable with using the black plug, which isn't as secure. It really isn't quite the right pitch either, as it is 2.54mm vs 2.50mm that the socket uses (close enough, in my opinion).

How to solve this? ALMOST every battery out there uses the same style balance plug that the 9X uses for its 8xAA holder. That means if we design a solution to use the balance plug, we're almost assured that whatever battery you choose, it already has the correct connector on it. That connector is [a knockoff of] a JST brand XH series. A 3 cell LiPO/LiFE uses a 4-position plug and a 2 cell uses a 3-position plug. So what about a small board that accepts either, and properly routes the power to the 9X socket?

I've drawn up my plans and I'll share very soon once I figure out how to get it off my napkin and into something electronic

Post by **s_mack** » Mon Sep 28, 2015 9:15 pm

OK, here it is. The pink areas are the two tiny boards. You'll have to imagine there are a red and black wire pre-soldered between them (that was too difficult to do in the 3D software). One part plugs into the existing battery socket and the wire runs through the inside of the radio around to the "bottom" open slot on the left (the "top" one is used by the 9Xtreme/SP board/SP Basic USB connector). The other part sits in the battery bay (glue it down?) and provides two sockets for use with either a 2S or 3S liPO/LiFE battery using a "standard" XH style balance plug. I say "standard" but really that's not the case. HobbyKing seems to exclusively use the XH for balance, but some higher-end batteries use other styles. I would say XH is by far and away the most common though.

I did some measurements and I believe everything will fit. This drawing is only semi accurate, so don't judge it too much. The orange 1500mAh LiFe battery should *just* fit, and certainly any smaller 3S or 2S could be used.

Thoughts?

bob195558 · Post by **bob195558** » Mon Sep 28, 2015 9:23 pm

s_mack wrote:Now that I look a little more carefully... are those wires exposed???? Or is that some grey paint or a scuff or something?

It's Bic Wite Out Quick Dry (paint).

I color paint code many of my plugs to help me to make sure I'm not plugging them together improperly.
When I was younger I had good eye sight and could see both close and far away very well.
But now I have a lot of difficulty seeing close up and I miss having the ability to see small things close up.

I guess logically it had to be a short, maybe the pin became bent just right.
Which could explain why 9x power circuit was not affected,
it never had received any reverse current in the first place.

Bob B.

bob195558 · Post by **bob195558** » Mon Sep 28, 2015 9:40 pm

It looks like it could fit OK.

Bob B.

Post by **s_mack** » Mon Sep 28, 2015 9:42 pm

It should. it would actually be a little easier on your wires because it wouldn't have to cram in at the side like that.

Of course, anyone that has their connector already sorted like that wouldn't need it really.

Post by **ShowMaster** » Mon Sep 28, 2015 9:50 pm

s_mack wrote:OK, here it is. The pink areas are the two tiny boards. You'll have to imagine there are a red and black wire pre-soldered between them (that was too difficult to do in the 3D software). One part plugs into the existing battery socket and the wire runs through the inside of the radio around to the "bottom" open slot on the left (the "top" one is used by the 9Xtreme/SP board/SP Basic USB connector). The other part sits in the battery bay (glue it down?) and provides two sockets for use with either a 2S or 3S liPO/LiFE battery using a "standard" XH style balance plug. I say "standard" but really that's not the case. HobbyKing seems to exclusively use the XH for balance, but some higher-end batteries use other styles. I would say XH is by far and away the most common though.

I did some measurements and I believe everything will fit. This drawing is only semi accurate, so don't judge it too much. The orange 1500mAh LiFe battery should *just* fit, and certainly any smaller 3S or 2S could be used.

Thoughts?

I like it! Any chance there's room on to add a reversed paralleled diode to burn open the trace? Or a Schottky 1A series diode into the cable? Sad, but someone will still find a way to reverse the balance connector on their battery. Especially if it doesn't match the pin out spacing and they add their own connector.
If only one could control the DIY cable makers ability to wire things up wrong before that first cup of morning coffee or tea, or late night brain dead soldering at 1Am, or in my case, evening wine. No power tools or wiring done after 5pm allowed in my "Lab".
[emoji485][emoji298]️

Post by **s_mack** » Mon Sep 28, 2015 10:02 pm

Well, that's kinda why I started to think of a non-tech way of resolving the issue... adding diodes increases voltage drop, which could be problematic. And then it only protects for reverse but not short. Personally, I see the problem stemming from the fact FlySky used a connector that is almost universally used as a 2S balance connector. So those using 2S LiPO naturally think that's what should go in there. Those not using a 2S LiPO are forced to rig up something on their own, and they get it "wrong" (commonly by using a 2.54mm spaced 2-pin connector and having it shifted over 1). By utilizing the almost-standard nature of the balance plug in the way I've described... I think it resolves both of those common scenarios. It virtually eliminates the need to modify the battery all, whether using a 2S or 3S.

Does it protect against all manners of stupid? No... no, someone can certainly find a way. But at that point, aren't we talking about someone that almost deliberately is trying to screw things up? Lol. At that point they didn't follow advice (get a battery with an extremely common XH balance connector), they didn't follow directions (pin out if the ignore previous advice), and they didn't follow common electrical practices (check your wiring if you ignored previous instructions). Maybe that person needs the $100 lesson?

The only downside I see remaining is if they go and use this setup with the stock 8xAA... but then that person has gone in circles and is really confused. At least if they did that, no poof because the hot wire would be n/c. So no harm, but they might be confused why nothing was powering up.

Post by **jhsa** » Mon Sep 28, 2015 11:34 pm

And then they ask here on the forum

Better than frying their radio..
I think your solution is great Steven. If there is a 2 cell and a 3 cell balance plug connector, lipo users won't have to DIY.. That leaves out the NiMh users like myself and a few others.

But I guess 90% of the people now use LiPo or LiFe batteries.

Post by **s_mack** » Mon Sep 28, 2015 11:40 pm

Yeah, hard to imagine a solution that works for everyone.

Post by **jhsa** » Mon Sep 28, 2015 11:52 pm

NiMh and NiCad users come from the old school so they normally know how to connect a battery

João

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